Medical instruments and devices are routinely sterilized by a high-pressure vapor sterilization method using water vapor saturated under a high pressure or by an ethylene oxide gas sterilization method using a chemical material such as ethylene oxide that does not cause thermal damage to tools or materials susceptible to heat.
More specifically, a high-pressure vapor sterilizer or an autoclave performs sterilization at a high temperature of about 120° C. or higher and may thus shorten the life of medical instruments and devices by causing deformation of medical appliances formed of a synthetic resin and blunting the sharp edges of medical appliances formed of steel. Particularly, expensive medical instruments and devices that are on the increase due to recent developments in surgical technology are generally susceptible to heat or moisture and are highly likely to be damaged during sterilization reprocessing. Thus, the high-pressure vapor sterilization method may not be a suitable option for such expensive medical instruments and devices.
An ethylene oxide gas sterilizer capable of minimizing thermal damage to medical instruments or devices can perform sterilization at low temperature, but requires a ventilation time of more than 12 hours after sterilization because of the possibility of any remaining ethylene oxide gas or the reaction products thereof causing carcinogenic or toxic substances. Also, the use of an ethylene oxide gas requires great care because an ethylene oxide gas is highly explosive, has been reported to serve as a genetic toxic substance causing mutations, and has even been known as a carcinogenic substance.
A sterilization method using hydrogen peroxide vapor boasts of various advantages, for example, a short sterilization time of about 30 to 60 minutes at a temperature of 40 to 50° C. and the release of harmless sterilization by-products to the human body or the environment, such as water and oxygen, and can address the shortcomings of a high-pressure vapor sterilizer and an ethylene oxide gas sterilizer.
The sterilization method using hydrogen peroxide vapor inevitably produces water vapor, and the water vapor passes through a vacuum pump while being released.
Some of the water vapor either continues to evaporate or is dissolved and released into the air. However, the water vapor cannot be completely discharged, and some of the water vapor may be trapped and accumulated in the oil of the vacuum pump.
Also, in a case in which a sterilization cycle involves the removal of moisture from a sterilant solution, the rate of accumulation moisture in the oil of the vacuum pump increases.
In this case, if too much water vapor is accumulated in the oil of the vacuum pump in the form of moisture, the water vapor may corrode the inner surfaces of the vacuum pump or deteriorate the vacuum exhaust performance.
Also, if too much moisture is contained in the oil of the vacuum pump, moisture cannot be sufficiently trapped by an oil mist trap section and the like while being released, thereby imposing a spatial restriction on the space where the equipment can be used.
Also, not only water vapor evaporated from a hydrogen peroxide solution, but also water vapor from a sterilization target washed and not sufficiently dried or having moisture adsorbed thereon, accelerates the trapping and accumulation of moisture in the vacuum pump.
However, the performance of a dry vacuum pump not using an oil is relatively poorer than the performance of an oil vacuum pump. Also, an expensive dry vacuum pump with high vacuum exhaust performance may not be suitable for vacuum-exhausting a container with a large volume due to its insufficient throughput.